Automated resuscitation device with ventilation sensing and prompting

ABSTRACT

A device for assisting a caregiver in delivering cardiac resuscitation to a patient, the device comprising a user interface configured to deliver prompts to a caregiver to assist the caregiver in delivering cardiac resuscitation to a patient; at least one sensor configured to detect the caregiver&#39;s progress in delivering the cardiac resuscitation, wherein the sensor is configured to provide a signal containing information indicative of ventilation; a memory in which a plurality of different prompts are stored, including at least one ventilation progress prompt to guide the rescuer&#39;s performance of ventilation; a processor configured to process the output of the sensor to determine a parameter descriptive of ventilation progress and to determine whether the ventilation progress prompt should be selected for delivery. Possible parameters descriptive of ventilation progress include ventilation rate, delivered tidal volume, and flow rate.

TECHNICAL FIELD

This invention relates to devices for assisting caregivers in deliveringcardiac resuscitation therapy to a patient (e.g., automatic externaldefibrillators).

BACKGROUND

Resuscitation treatments for patients suffering from cardiac arrestgenerally include clearing and opening the patient's airway, providingrescue breathing for the patient, and applying chest compressions toprovide blood flow to the victim's heart, brain and other vital organs.If the patient has a shockable heart rhythm, resuscitation also mayinclude defibrillation therapy. The term basic life support (BLS)involves all the following elements: initial assessment; airwaymaintenance; expired air ventilation (rescue breathing); and chestcompression. When all these elements are combined, the termcardiopulmonary resuscitation (CPR) is used.

There are many different kinds of abnormal heart rhythms, some of whichcan be treated by defibrillation therapy (“shockable rhythms”) and somewhich cannot (non-shockable rhythms”). For example, most ECG rhythmsthat produce significant cardiac output are considered non-shockable(examples include normal sinus rhythms, certain bradycardias, and sinustachycardias). There are also several abnormal ECG rhythms that do notresult in significant cardiac output but are still considerednon-shockable, since defibrillation treatment is usually ineffectiveunder these conditions. Examples of these non-shockable rhythms includeasystole, electromechanical disassociation, and other pulselesselectrical activity. Although a patient cannot remain alive with thesenon-viable, non-shockable rhythms, applying shocks will not help convertthe rhythm. The primary examples of shockable rhythms, for which thecaregiver should perform defibrillation, include ventricularfibrillation, ventricular tachycardia, and ventricular flutter.

After using a defibrillator to apply one or more shocks to a patient whohas a shockable ECG rhythm, the patient may nevertheless remainunconscious, in a shockable or non-shockable, perfusing or non-perfusingrhythm. If a non-perfusing rhythm is present, the caregiver may thenresort to performing CPR for a period of time in order to providecontinuing blood flow and oxygen to the patient's heart, brain and othervital organs. If a shockable rhythm continues to exist or developsduring the delivery of CPR, further defibrillation attempts may beundertaken following this period of cardiopulmonary resuscitation. Aslong as the patient remains unconscious and without effectivecirculation, the caregiver can alternate between use of thedefibrillator (for analyzing the electrical rhythm and possibly applyinga shock) and performing cardiopulmonary resuscitation (CPR). CPRgenerally involves a repeating pattern of five or fifteen chestcompressions followed by a pause during which two rescue breaths aregiven.

Defibrillation can be performed using an AED. The American HeartAssociation, European Resuscitation Council, and other similar agenciesprovide protocols for the treatment of victims of cardiac arrest thatinclude the use of AEDs. These protocols define a sequence of steps tobe followed in accessing the victim's condition and determining theappropriate treatments to be delivered during resuscitation. Caregiverswho may be required to use an AED are trained to follow these protocols.

Most automatic external defibrillators are actually semi-automaticexternal defibrillators (SAEDs), which require the caregiver to press astart or analyze button, after which the defibrillator analyzes thepatient's ECG rhythm and advises the caregiver to provide a shock to thepatient if the electrical rhythm is shockable. The caregiver is thenresponsible for pressing a control button to deliver the shock.Following shock delivery, the SAED may reanalyze the patient's ECGrhythm, automatically or manually, and advise additional shocks orinstruct the caregiver to check the patient for signs of circulation(indicating that the defibrillation treatment was successful or that therhythm is non-shockable) and to begin CPR if circulation has not beenrestored by the defibrillation attempts. Fully automatic externaldefibrillators, on the other hand, do not wait for user interventionbefore applying defibrillation shocks. As used below, automatic externaldefibrillators (AED) include semi-automatic external defibrillators(SAED).

Both types of defibrillators typically provide an auditory “stand clear”warning before beginning ECG analysis and/or the application of eachshock. The caregiver is then expected to stand clear of the patient(i.e., stop any physical contact with the patient) and may be requiredto press a button to deliver the shock. The controls for automaticexternal defibrillators are typically located on a resuscitation devicehousing.

AEDs are typically used by trained medical or paramedic caregivers, suchas physicians, nurses, emergency medical technicians, fire departmentpersonnel, and police officers. The ready availability of on-site AEDsand caregivers trained to operate them is important because a patient'schances of survival from cardiac arrest decrease by approximately 10%for each minute of delay between occurrence of the arrest and thedelivery of defibrillation therapy.

Trained lay caregivers are a new group of AED operators. For example,spouses of heart attack victims may become trained as lay caregivers.Lay caregivers rarely have opportunities to defibrillate or deliver CPR,and thus they can be easily intimidated by an AED during a medicalemergency. Consequently, such lay providers may be reluctant to purchaseor use AEDs when needed, or might tend to wait for an ambulance toarrive rather than use an available AED, out of concern that the layprovider might do something wrong.

Some trained medical providers, e.g., specialists such as obstetricians,dermatologists, and family care practitioners, also rarely have theopportunity to perform CPR and/or defibrillate, and thus may be uneasyabout doing so. Concerns about competence are exacerbated if training isinfrequent, leading the caregiver to worry that he or she may not beable to remember all of the recommended resuscitation protocol stepsand/or their correct sequence.

Similarly, both medical and lay caregivers may be hesitant to provideCPR and rescue breathing, or may be unsure when these steps should beperformed, particularly if their training is infrequent and they rarelyhave the opportunity to use it.

It is well known to those skilled in the art, and has been shown in anumber of studies, that CPR is a complex task with both poor initiallearning as well as poor skill retention, with trainees often losing 80%of their initial skills within 6-9 months. It has thus been the objectof a variety of prior art to attempt to improve on this disadvantageouscondition. Aids in the performance of chest compressions are describedin U.S. Pat. Nos. 4,019,501, 4,077,400, 4,095,590, 5,496,257, 6,125,299,and 6,306,107, 6,390,996. U.S. Pat. Nos. 4,588,383, 5,662,690 5,913,685,4,863,385 describe CPR prompting systems. AEDs have always includedvoice prompts as well as graphical instructions on flip charts orplacards since the earliest commercial versions in 1974 to provide bothcorrect timing and sequence for the complex series of actions requiredof the rescuer (caregiver) as well as placement of the defibrillationelectrodes. U.S. patent application Ser. No. 09/952,834 and U.S. Pat.Nos. 6,334,070 and 6,356,785 describe defibrillators with an increasedlevel of prompting including visual prompts either in the form ofgraphical instructions presented on a CRT or on printed labels withbacklighting or emissive indicia such as light emitting diodes. AEDssince the 1970s have used the impedance measured between thedefibrillation electrodes to determine the state of the AED as well asappropriate messages to deliver to the rescuer (e.g. “Attach Electrodes”if the initial prompts on the unit have been delivered and the impedanceremains greater than some specified threshold) or to determine if thereis excessive patient motion (as in U.S. Pat. No. 4,610,254.) U.S. Pat.No. 5,700,281 describes a device which uses the impedance of theelectrodes to determine the state of the AED for delivering messagessuch as “Attach Electrodes”. Enhanced prompting disclosed in thesepatents provides some benefit to the rescuer in improved adherence tothe complex protocol required of them to successfully revive a cardiacarrest patient, but the enhanced prompting is usually not sufficient inreal world situations. U.S. Pat. Nos. 5,662,690 and 6,356,785 (and thecommercially available OnSite defibrillator) attempts to improveprompting by providing a rescuer-accessible “Help” key that initiatesmore detailed prompting in cases in which the rescuer or test subject isconfused. But testing has shown that with the heightened level ofanxiety that accompanies a real cardiac arrest, rescuers rarely rememberto press such a Help key. Even notifying the rescuer at the beginning ofthe protocol to press the Help key does not help a the confused rescuerpress the Help key. Furthermore, even if the Help key is pressed, it isnecessary to have the rescuer work through a series of user interfaceinteractions via a touchscreen, softkeys or other input means, for thehelp software to determine at which step the rescuer is in need ofadditional instructions. Putting the user through these interactionswith the help software detracts from the rescuer's ability to provideaid to the patient, and thus delays delivery of therapy.

AEDs have also been solely focused on defibrillation, which, while itprovides the best treatment for ventricular fibrillation and certaintachycardias, is of no therapeutic benefit for the 60% of the cardiacarrest patients presenting in pulseless electrical activity (PEA) orasystole. As AEDs are becoming more prevalent in the home, there arealso a host of other health problems that occur such as first aid aswell as incidents related to chronic conditions such as asthma, diabetesor cardiac-related conditions for which the AED is of no benefit.

It has been found in several clinical studies that supposedly trainedpersonnel such as physicians, nurses, and paramedics trained in advancedcardiac life support (ACLS) do not provide optimal cardiac compressions,either with respect to rate or depth of compressions. This group ofcaregivers has also been shown in studies to provide ventilations at anexcessive rate. Over-ventilation has been shown to result in excessiveintra-thoracic pressure, which impedes the diastolic filling cycle andreduces blood flow and coronary and brain perfusion pressures duringCPR. European Patent EP 1157717B1 and U.S. Pat. No. 6,821,254 describesystems for determining ventilation rates from an AC, small-signaltransthoracic impedance (TTI) measured between the defibrillationelectrode pads. A known limitation of this measurement method is theexcessive noise present on the TTI signal due to a variety of noisesources, includingbody movement, capacitive fluctuations, andelectrolyte charge transfer during chest compressions. Advancedcaregivers also desire an accurate measure of “tidal volume”—the actualvolume of gas transferred in and out of the lungs—to better assess thecare provided and to make appropriate clinical decisions. Ventilationmeasurement based solely on TTI is, however, incapable of providingaccurate measurements of tidal volume, unless an inconvenient initialcalibration procedure is performed, due to the normal randominter-patient anatomical variations.

SUMMARY

In a first aspect, the invention features a device for assisting acaregiver in delivering cardiac resuscitation to a patient, the devicecomprising a user interface configured to deliver prompts to a caregiverto assist the caregiver in delivering cardiac resuscitation to apatient, at least one sensor configured to detect the caregiver'sprogress in delivering the cardiac resuscitation, wherein the sensor isconfigured to provide a signal containing information indicative ofventilation, a memory in which a plurality of different prompts arestored, including at least one ventilation progress prompt to guide therescuer's performance of ventilation, a processor configured to processthe output of the sensor to determine a parameter descriptive ofventilation progress and to determine whether the ventilation progressprompt should be selected for delivery.

Preferred implementations of this aspect of the invention mayincorporate one or more of the following. The parameter descriptive ofventilation progress may be ventilation rate, and the ventilationprogress prompt may comprise an instruction pertaining to varying theventilation rate. The parameter descriptive of ventilation progress maybe delivered tidal volume, and the ventilation progress prompt maycomprise an instruction pertaining to varying the delivered tidalvolume. The parameter descriptive of ventilation progress may be flowrate, and the ventilation progress prompt may comprise an instructionpertaining to varying the flow rate. The sensor may comprise anaccelerometer, and the processor may process the output of theaccelerometer to distinguish between ventilations and chestcompressions. The sensor may comprise a pressure sensor, and theprocessor may process the output of the pressure sensor to determine theparameter descriptive of ventilation progress. There may be a pluralityof other sensors configured to detect the caregiver's progress indelivering the cardiac resuscitation, wherein each of the plurality ofsensor may be other than an electrode connected to the body. Theprocessor may be configured to vary the time at which prompts aredelivered based on the progress detected by the sensor. The devicefurther may comprise one or more additional sensors configured to detectthe caregiver's progress in delivering the therapy, wherein the one ormore additional sensors may comprise an electrode in electrical contactwith the body. The processor may select a series of more detailedprompts for delivery to a user when progress is slower than apredetermined pace. The processor may be configured to slow down therate at which prompts are delivered when progress is slower than apredetermined pace. The user interface may deliver at least some of theprompts as oral instructions to be heard by the caregiver. The userinterface may deliver at least some of the prompts as visualinstructions to be seen by the caregiver. The user interface maycomprise an electronic display. The electronic display may provide aseries of images. The device may further comprise an automatic externaldefibrillator. The oral prompts may be associated with a series ofgraphics and may be given sequentially to guide the caregiver through asequence of steps. The visual prompts may be delivered as a series ofgraphics with the sequential illumination of light sources to guide thecaregiver through the sequence of graphics. The device may furthercomprise a processing system that measures and records the timesrequired for a user to complete a sequence of steps and/or sub-steps ina protocol, and, based on the measured times adjusts the rate of theprompting delivered. The adjusting may be based on a comparison of themeasured times with a set of stored values.

In a second aspect, the invention features an automatic externaldefibrillation device for delivering defibrillation shocks to a patientand for assisting a caregiver in delivering cardiac resuscitation to thepatient, the device comprising an electrode pad supporting at least onedefibrillation electrode, the pad being configured to be adhesivelyapplied to the chest of the patient, at least one pressure sensorconfigured to detect information relating to the caregiver's delivery ofventilations to the patient, wherein at least a portion of the pressuresensor is mounted on the electrode pad, a processor configured toprocess the output of the pressure sensor to determine a parameterdescriptive of ventilation progress.

Preferred implementations of this aspect of the invention mayincorporate one or more of the following. The parameter descriptive ofventilation progress may be ventilation rate, and the ventilationprogress prompt may comprise an instruction pertaining to varying theventilation rate. The parameter descriptive of ventilation progress maybe delivered tidal volume, and the ventilation progress prompt maycomprise an instruction pertaining to varying the delivered tidalvolume. The parameter descriptive of ventilation progress may be flowrate, and the ventilation progress prompt may comprise an instructionpertaining to varying the flow rate. At least one tube may run from thepressure sensor on the electrode pad to an adapter configured to bepositioned in the vicinity of the patient's mouth, and the tube andadapter may be configured so that a pressure associated withventilations is conveyed through the tube to the pressure sensor on theelectrode pad assembly. The device may further comprise a second tuberunning from the pressure sensor to the adapter, and the adapter andtubes may be configured to measure a differential pressure associatedwith ventilations. The device may further comprise at least oneindicator light on the electrode pad assembly to convey informationabout delivered ventilations. The information may comprise whetherventilation rate is within a predetermined range of acceptableventilation rates. The information may comprise an indication of thedelivered tidal volume.

In a third aspect, the invention features a device for assisting acaregiver in delivering cardiac resuscitation to a patient, the devicecomprising a user interface configured to deliver prompts to a caregiverto assist the caregiver in delivering cardiac resuscitation to apatient, at least two sensors configured to provide signals from whichinformation can be derived on the placement of an ET tube in thepatient, a memory in which a plurality of different prompts are stored,including at least a first ET tube placement prompt providing a firstindication as to the placement of the ET tube, a processor configured toprocess the outputs of the sensors to determine the ET tube placementand to determine whether the first ET tube placement prompt should bedelivered.

Preferred implementations of this aspect of the invention mayincorporate one or more of the following. The first ET tube placementprompt may comprise a prompt indicating that the ET tube is notcorrectly placed in the patient's trachea. The sensors may comprise apressure sensor configured to detect the timing of ventilationsdelivered to the ET tube and an accelerometer may be configured todetect sternal motion in the patient. The sensors may comprise apressure sensor configured to detect the timing of ventilationsdelivered to the ET tube and a TTI sensor may be configured to detectchanges in the transthoracic impedance of the patient. One of thesensors may be configured to detect the timing of ventilations deliveredto the ET tube, another of the sensors may be configured to detect thetiming of sternal movement in the patient or of change in transthoracicimpedance of the patient, and the processor may be configured to comparethe relative timing of ventilations and sternal movements ortransthoracic impedance changes.

Among the many advantages of the invention (some of which may beachieved only in some of its various aspects and implementations) arethat the invention provides a more effective means of measuringventilations. Accurate tidal volumes can conveniently be measured, andthe ventilation measurements are more immune to noise.

Other features and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an AED with its cover on.

FIG. 2 is a perspective view of the AED of FIG. 1 with the coverremoved.

FIG. 3 is a block diagram of the AED.

FIG. 3A is a circuit schematic showing filtering of the ventilationpressure sensor output.

FIG. 4 is a plan view of the graphical interface decal used on the coverof the AED of FIG. 1.

FIG. 5 is a plan view of the graphical interface decal used on thedevice housing of the AED of FIG. 1, as shown in FIG. 2.

FIG. 6 a-6 e are flow charts indicating audio prompts provided duringuse of the AED of FIG. 1 and steps to be performed by the caregiver inresponse to the graphical and audio prompts.

FIGS. 7 a and 7 b list the audio prompts used in the flowcharts shown inFIGS. 6 a-6 e.

FIG. 8 is an exploded perspective view of the cover and housing.

FIG. 9 is a side plan view of the cover indicating angle ‘A’.

FIGS. 10 a and 10 b are side views of a patient with and without thecover placed beneath the shoulders, to show the effect on the patient'sairway of placing the cover beneath the shoulders.

FIG. 11 is a plan view of a decal providing graphical instructions onthe cover for placing the cover under a patient's shoulders.

FIG. 12 shows an integrated electrode pad with integrated ventilationpressure sensor.

FIG. 13 is another view of an electrode pad.

FIG. 14 is an isometric view of an electrode well along one side of thehousing.

FIG. 15 is a schematic of the electronics contained in the integratedelectrode pad of FIG. 12.

FIG. 16 is an isometric view of a first-aid kit implementation.

DETAILED DESCRIPTION

There are a great many possible implementations of the invention, toomany to describe herein. Some possible implementations that arepresently preferred are described below. It cannot be emphasized toostrongly, however, that these are descriptions of implementations of theinvention, and not descriptions of the invention, which is not limitedto the detailed implementations described in this section but isdescribed in broader terms in the claims.

The terms “caregiver”, “rescuer” and “user” are used interchangeably andrefer to the operator of the device providing care to the patient.

Referring to FIGS. 1 and 2, an automated external defibrillator (AED) 10includes a removable cover 12 and a device housing 14. The defibrillator10 is shown with cover 12 removed in FIG. 2. An electrode assembly 16(or a pair of separate electrodes) is connected to the device housing 14by a cable 18. Electrode assembly 16 is stored under cover 12 when thedefibrillator is not in use.

Referring to FIG. 3, the AED includes circuitry and software 20 forprocessing, a user interface 21 including such elements as a graphical22 or text display 23 or an audio output such as a speaker 24, andcircuitry and/or software 25 for detecting a caregiver's progress indelivering therapy—e.g., detecting whether one or more of a series ofsteps in a protocol has been completed successfully In some preferredimplementations, the detecting also includes the ability to determineboth whether a particular step has been initiated by a user andadditionally whether that particular step has been successfullycompleted by a user. Based on usability studies in either simulated oractual use, common user errors are determined and specific detectionmeans are provided for determining if the most prevalent errors haveoccurred.

If it is determined that the current step in the protocol has not beencompleted, then the processor will pause the currently-scheduledsequence of instructions. If, for instance, it has been determined thata particular step has been initiated but not completed, but none of thecommon errors has occurred subsequent to initiation of the particularstep, then the processor may simply provide a pause while waiting forthe user to complete the step. If, after waiting for a predeterminedperiod of time based on prior usability tests, there has been nodetection of the step completion, the processor may initiate a moredetailed set of prompts, typically at a slower sequence rate, describingthe individual sub-steps that comprise a particular step. If one of thecommon errors is detected while waiting for completion of the step, theprocessor may initiate a sequence of instructions to correct the user'sfaulty performance.

Device housing 14 includes a power button 15 and a status indicator 17.Status indicator 17 indicates to the caregiver whether the defibrillatoris ready to use.

The cover 12 includes a cover decal 30 (FIGS. 1 and 4) including a logo31 and a series of graphics 32, 34 and 36. Logo 31 may provideinformation concerning the manufacturer of the device and that thedevice is a defibrillator (e.g., “ZOLL AED”, as shown in FIG. 1,indicating that the device is a Semi-Automatic External Defibrillatoravailable from Zoll Medical). Graphics 32, 34 and 36 lead the caregiverthrough the initial stages of a cardiac resuscitation sequence asoutlined in the AHA's AED treatment algorithm for Emergency Cardiac Carepending arrival of emergency medical personnel . (See “Guidelines 2000for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.Supplement to Circulation,” Volume 102, Number 8, Aug. 22, 2000, pp.I-67.) Thus, graphic 32, showing the caregiver and patient, indicatesthat the caregiver should first check the patient for responsiveness,e.g., by shaking the patient gently and asking if the patient is okay.Next, graphic 34, showing a telephone and an emergency vehicle,indicates that the caregiver should call for emergency assistance priorto administering resuscitation. Finally, graphic 36 indicates that afterthese steps have been performed the caregiver should remove the cover 12of the defibrillator, remove the electrode assembly 16 stored under thelid, and turn the power on by depressing button 15. The graphics arearranged in clockwise order, with the first step in the upper left,since this is the order most caregivers would intuitively follow.However, in this case the order in which the caregiver performs thesteps is not critical, and thus for simplicity no other indication ofthe order of steps is provided.

The device housing includes a device housing decal 40, shown in FIGS. 2and 5. The graphics are configured to lead the caregiver through theentire resuscitation sequence, as will be explained below with referenceto FIGS. 6 a-6 e. Decal 40 also includes a center graphic 50, whichincludes representations of a hand and a heart. Center graphic 50overlies a treatment button which, when depressed, causes thedefibrillator to deliver a defibrillating shock to the electrodeassembly 16.

Each of the graphics on device housing decal 40 is accompanied by alight source that can be temporarily illuminated to indicate that theilluminated step should be performed at that particular time. Theselight sources guide the caregiver, step-by-step, through theresuscitation sequence, indicating which graphic should be viewed ateach point in time during resuscitation.

The light source for each of the graphics 42-49 is preferably anadjacent LED (LEDs 56, FIG. 2). The heart may be translucent and backlitby a light source in the device housing (not shown). Alternatively, theheart may include an adjacent LED (not shown) and/or the hand mayinclude an LED 57 as shown. Programmable electronics within the devicehousing 14 are used to determine when each of the light sources shouldbe illuminated.

In some preferred implementations, a liquid crystal display 51 is usedto provide the more detailed graphical prompts when a user is unable tocomplete the rescue sequence on their own. In these implementations, thepurpose of the printed graphics is to provide a more general indicationof the current step in the overall sequence, e.g. airway graphics 44provides an indication that the rescuer should be performing the “OpenAirway. Check for Breathing.” sub-sequence, but may not provide adetailed enough description for someone who has forgotten the correctactions to perform. In an alternative embodiment, the graphicalinstructions may be provided by a larger version of the liquid crystaldisplay (LCD) 51 whereby the LED-lit printed instructions are eliminatedor removed and most or all of the graphical instructions are provided bythe LCD 30. In this case, the LCD 51 will automatically show the moredetailed instructions when it determines that the user is unable toproperly perform the action.

The programmable electronics may also provide audio prompts, timed tocoincide with the illumination of the light sources and display ofimages on the liquid crystal display 51, as will also be discussed belowwith reference to FIGS. 6 a and 6 e.

The cover 12 is constructed to be positioned under a patient's neck andshoulders, as shown in FIGS. 10 a and 10 b, to support the patient'sshoulders and neck in a way that helps to maintain his airway in an openposition, i.e., maintaining the patient in the head tuck-chin liftposition. The cover is preferably formed of a relatively rigid plasticwith sufficient wall thickness to provide firm support duringresuscitation. Suitable plastics include, for example, ABS,polypropylene, and ABS/polypropylene blends.

Prior to administering treatment for cardiac arrest, the caregivershould make sure that the patient's airway is clear and unobstructed, toassure passage of air into the lungs. To prevent obstruction of theairway by the patient's tongue and epiglottis (e.g., as shown in FIG. 10a), it is desirable that the patient be put in a position in which theneck is supported in an elevated position with the head tilted back anddown. Positioning the patient in this manner is referred to in theAmerican Heart Association Guidelines for Cardiopulmonary Resuscitationand Emergency Cardiovascular Care as the “head tilt-chin lift maneuver.”The head tilt-chin lift position provides a relatively straight, openairway to the lungs through the mouth and trachea. However, it may bedifficult to maintain the patient in this position during emergencytreatment.

The cover 12 has an upper surface 524 that is inclined at an angle A(FIG. 9 a) of from about 10 to 25 degrees, e.g., 15 to 20 degrees, so asto lift the patient's shoulders and thereby cause the patient's head totilt back. The upper surface 524 is smoothly curved to facilitatepositioning of the patient. A curved surface, e.g., having a radius ofcurvature of from about 20 to 30 inches, generally provides betterpositioning than a flat surface. At its highest point, the cover 12 hasa height H (FIG. 9) of from about 7.5 to 10 cm. To accommodate the widthof most patients' shoulders, the cover 12 preferably has a width W (FIG.9) of at least 6 inches, e.g., from about 6 to 10 inches. If the cover12 is not wide enough, the patient's neck and shoulders may move aroundduring chest compressions, reducing the effectiveness of the device. Theedge of the cover may also include a lip 11 (FIG. 9) or gasket (notshown) to prevent water from entering the housing when the cover is inplace. The positions shown in FIGS. 10 a and l0 b (a patient in the headlift-chin tilt position and a patient with a closed airway) are alsoshown in the AHA Guidelines for Cardiopulmonary Resuscitation andEmergency Cardiovascular Care, Aug. 22, 2000, p. I-32, FIGS. 7 and 8.

The cover 12 is provided with one or more sensors for determining if thepatient's shoulders have been properly positioned on the cover 12.Referring to FIG. 8, two photoelectric sensors 156, 157 are used todetermine if the cover has been placed underneath the patient's back.The sensors 156, 157 are located along the acute edge of the cover 12,with one facing inward and one facing outward with the cable 155providing both power to the sensors 156, 157 as well as detection of thesensor output. If the cover 12 is upside down, the inner sensor 156 willmeasure a higher light level than the outer sensor 157; if the cover hasbeen placed with the acute edge facing toward the top of the patient'shead, then the outer sensor 157 will measure higher than the innersensor 156 and will also exceed a pre-specified level. In the case of aproperly positioned cover, both inner 156 and outer sensor 157 outputswill be below a pre-specified level. In another embodiment, thedetections means is provided by a pressure sensor 158 located underneaththe cover decal. Referring to FIG. 6 c, if the processing means 20detects that the cover is upside down, it will cause an audible promptto be delivered to the user that is more detailed than the originalprompt. The processing means 20 will also slow down the rate of speechof the audio prompts. If the cover is still upside down after apredetermined period of time, the processing means 20 will deliver aneven more detailed message on how to properly place the cover. If, afterthree attempts to get the user to properly position the cover 12, theprocessing means 20 will deliver the next audio prompt 160 withoutfurther waiting for proper placement of the cover 12.

In the preferred embodiment, the defibrillator includes communicationcapability such as cell phone, global positioning system (GPS) orsimpler wireless phone capability. Preferably, both cell phone and GPSare included in the device. The cell phone is preconfigured toautomatically dial the Emergency Response Center (ERC) in the communityin which it is located such as “911” in much of the United States. Thecell phone service is chosen which is able to provide voice, data, aswell as GPS capability. Thus in response to a command by the device to“Call 911 by Pressing the Phone button”, the device automatically dials911 and the built-in speaker 458 and microphone 459 on the devicefunction to provide speakerphone capability. If a connection issuccessfully made to the emergency response center, the device transmitsits exact location based on its GPS capability and also can transmit tothe response center the status of the defibrillator. In more advancedmodes, the emergency response center can remotely control the operationof the defibrillator via the bi-directional data capability. When aconnection is made to the ERG and emergency response personnel (ERP),the automatic voice prompting of the defibrillator can be remotelyde-activated by the ERP so as not to distract the rescuer from theinstructions given by the ERP. While coaching the rescuer via thespeakerphone capability in the defibrillator, the ERP can utilize theresponsive feedback prompting functionality of the device to providemore accurate coaching of the rescuer. It is well known, however, thatcell phone and other wireless communication methods are not especiallyreliable even under the best circumstances, and are often completelyunavailable in industrial facilities, basements, etc., thus it isimportant to provide a means of automatically reverting to the modewherein the device provides all responsive feedback prompts to the userwhen the processor detects that the communication link has been lost.Additional prompts will also be provided to the user to assuage anyconcern they might have that the connection to the human expert has beenlost (e.g. “Communication has been temporarily lost to 911 personnel.Don't worry. This AED is able to perform all steps and help you throughthis procedure.”). When a communication link has been lost, the devicewill preferably automatically begin recording all device and patientstatus as well as all audio received by the built-in microphone. If thecommunication link is subsequently reacquired, the device willpreferably automatically transmit the complete event, including patient,device and audio data, acquired during the time communication was notavailable, providing ERP valuable data to help in their medicaldecision-making. The ERP may remotely control the defibrillator via abi-directional communication link that transmits both voice and data.

In another embodiment, a remote computer located at the ERC, that ismore capable than the processor in the device may provide the remotedecision-making capability. The remote computer would run artificialintelligence software utilizing such techniques, e.g., as fuzzy logic,neural nets and intelligent agents to provide prompting to the user.

FIG. 6 a illustrates, in flow chart form, the default graphical andaudio prompts provided by the device for a caregiver performingresuscitation. The prompts shown in the figure do not include responsivefeedback prompts by the device that provide more detailed instructionsdepending on whether particular sequences have been successfullycompleted by the caregiver. The text in boxes indicates steps performedby the caregiver. The text in caption balloons, with ear symbols,indicates audio prompts generated by the defibrillator. FIGS. 6 b-6 eprovide flowcharts of more detailed responsive feedback prompts (thecontent of which are shown in FIGS. 7 a, 7 b) that may be provided tosupplement the steps of calling for help, open airway/check forbreathing, and defibrillation electrode application.

Thus, when a person collapses and a caregiver suspects that the personis in cardiac arrest 100, the caregiver first gets the defibrillator andturns the power on 102. If the unit passes its internal self tests, andis ready for use, this will be indicated by indicator 17, as discussedabove. Next, the defibrillator prompts the caregiver with anintroductory audio message, e.g., “Stay calm. Listen carefully.” (Audioprompt 104.) Shortly thereafter, the defibrillator will prompt thecaregiver with an audio message indicating that the caregiver shouldcheck the patient for responsiveness (audio prompt 106). Simultaneously,the LED adjacent graphic 42 will light up, directing the caregiver tolook at this graphic. Graphic 42 will indicate to the caregiver that sheshould shout “are you OK?” and shake the person (step 108) in order todetermine whether the patient is unconscious or not.

After a suitable period of time has elapsed (e.g., 2 seconds), if thecaregiver has not turned the defibrillator power off (as would occur ifthe patient were responsive), the defibrillator will give an audioprompt indicating that the caregiver should call for help (audio prompt110). Simultaneously, the LED adjacent graphic 42 will turn off and theLED adjacent graphic 43 will light up, directing the caregiver'sattention to graphic 43. Graphic 43 will remind the caregiver to callemergency personnel (step 112), if the caregiver has not already doneso.

After a suitable interval has been allowed for the caregiver to performstep 112 (e.g., 2 seconds since audio prompt 110) the defibrillator willgive an audio prompt indicating that the caregiver should open thepatient's airway and check whether the patient is breathing (audioprompt 114). The LED adjacent graphic 43 will turn off, and the LEDadjacent graphic 44 will light up, directing the caregiver's attentionto graphic 44, which shows the proper procedure for opening a patient'sairway. This will lead the caregiver to lift the patient's chin and tiltthe patient's head back (step 116). The caregiver may also position anairway support device under the patient's neck and shoulders, ifdesired, as discussed below with reference to FIGS. 10 a, 10 b. Thecaregiver will then check to determine whether the patient is breathing.

After a suitable interval (e.g., 15 seconds since audio prompt 114), thedefibrillator will give an audio prompt indicating that the caregivershould check for signs of circulation (audio prompt 118), the LEDadjacent graphic 44 will turn off, and the LED adjacent graphic 45 willlight up. Graphic 45 will indicate to the caregiver that the patientshould be checked for a pulse or other signs of circulation asrecommended by the AHA for lay rescuers (step 120).

After a suitable interval (e.g., 5 to 7 seconds since audio prompt 118),the defibrillator will give an audio prompt indicating that thecaregiver should attach electrode assembly 16 to the patient (audioprompt 122), the LED adjacent graphic 45 will turn off, and the LEDadjacent graphic 46 will light up. Graphic 46 will indicate to thecaregiver how the electrode assembly 16 should be positioned on thepatient's chest (step 124).

At this point, the LED adjacent graphic 47 will light up, and thedefibrillator will give an audio prompt indicating that the patient'sheart rhythm is being analyzed by the defibrillator and the caregivershould stand clear (audio prompt 126). While this LED is lit, thedefibrillator will acquire ECG data from the electrode assembly, andanalyze the data to determine whether the patient's heart rhythm isshockable. This analysis is conventionally performed by AEDs.

If the defibrillator determines that the patient's heart rhythm is notshockable, the defibrillator will give an audio prompt such as “No shockadvised” (audio prompt 128). The LEDs next to graphics 48 and 49 willthen light up, and the defibrillator will give an audio promptindicating that the caregiver should again open the patient's airway,check for breathing and a pulse, and, if no pulse is detected by thecaregiver, then commence giving CPR (audio prompt 130, step 132).Graphics 48 and 49 will remind the caregiver of the appropriate steps toperform when giving CPR.

Alternatively, if the defibrillator determines that the patient's heartrhythm is shockable, the defibrillator will give an audio prompt such as“Shock advised. Stand clear of patient. Press treatment button.” (Audioprompt 134.) At the same time, the heart and/or hand will light up,indicating to the caregiver the location of the treatment button. Atthis point, the caregiver will stand clear (and warn others, if present,to stand clear) and will press the heart, depressing the treatmentbutton and administering a defibrillating shock (or a series of shocks,as determined by the defibrillator electronics) to the patient (step136).

After step 136 has been performed, the defibrillator will automaticallyreanalyze the patient's heart rhythm, during which audio prompt 126 willagain be given and graphic 47 will again be illuminated. The analyze andshock sequence described above will be repeated up to three times if ashockable rhythm is repeatedly detected or until the defibrillator isturned off or the electrodes are removed. After the third shock has beendelivered, the device will illuminate LEDs 48 and 49 and issue the audioprompts 130/132. The device will keep LEDs 48 and 49 illuminated for aperiod of approximately one minute indicating that if CPR is performed,it should be continued for the entire minute. “Continue CPR” audioprompts may be repeated every 15-20 seconds during this period toinstruct the user to continue performing chest compressions and rescuebreathing.

After approximately one minute has elapsed, the device will extinguishLEDs 48 and 49 and illuminate LED 47. Audio prompt 126 (stand clear,analyzing rhythm) will also be issued and a new sequence of up to threeECG analyses/shocks will begin.

If the caregiver detects circulation during step 132, the caregiver mayturn off the defibrillator and/or remove the electrodes. Alternatively,the caregiver may not perform further CPR, but nonetheless allow thedevice to reanalyze the ECG after each one minute CPR period in order toprovide repeated periodic monitoring to ensure the patient continues tohave a non-shockable rhythm.

Thus, in the continuing presence of a shockable rhythm, the sequence ofthree ECG analyses and three shocks, followed by one minute of CPR, willcontinue indefinitely. If, instead, a non-shockable rhythm is or becomespresent, the sequence will be analyze/no shock advised, one minute ofCPR, analyze/no shock advised, one minute of CPR, etc. When a shock iseffective in converting the patient's heart rhythm to a heart rhythmthat does not require further defibrillating treatment, the sequencewill be: analyze/shock advised, shock (saves patient), analyze/no shockadvised, one minute CPR period (if pulse is detected then caregiver willnot do CPR during this period), analyze/no shock advised, one minute CPRperiod, etc., continuing until the caregiver turns the defibrillator(e.g., if the caregiver detects a pulse) or the electrodes are removed.

If electrode contact is lost at any time (as determined by the impedancedata received from the electrode assembly), this will result in anappropriate audio prompt, such as “check electrodes” and illumination ofthe LED adjacent graphic 46. The electrodes package 16 may be stored ina well 222 (FIG. 14) that is structurally integrated with the housing 14or may be a separate pouch.

It has also been discovered that a not-insignificant portion ofcaregivers are unable to open the packaging for the electrodes;therefore, a sensor may be provided to determine if the electrodepackage 16 has been opened. If detection of the electrode packageopening has not occurred within a predetermined period of time, the unitwill provide more detailed instructions to assist the user in openingthe packaging 16.

Referring to FIGS. 12 and 13, in preferred implementations, a means isprovided of detecting and differentiating successful completion ofmultiple steps of electrode application: (1) taking the electrodes 208out of the storage area 222 or pouch; (2) peeling the left pad 212 fromthe liner; (3) peeling the right pad 214 from the liner; (4) applyingthe left pad 212 to the patient; and (5) applying the right pad 214 tothe patient. Referring to FIGS. 12 and 13, a package photosensor 210 isprovided on the outer face of the electrode backing 220. Detection thatthe electrode 208 is sealed in the storage area is determined by thephotosensor output being below a threshold. A photoemitter/photosensor(PEPS) 223 combination is embedded into each electrode facing towardsthe liners 216. The liner 216 is constructed so that a highly reflectivealuminized Mylar, self-adhesive disk 224 is applied to the liner 216 inthe location directly beneath the PEPS 223. The reflective disk 224 iscoated with a silicone release material on the side in contact with theelectrode 208 so that it remains in place when the electrode 208 isremoved from the liner. In such a configuration, the processor is fullycapable of differentiating substantially the exact step in the protocolrelated to electrode application. When the package photosensor 210detects light above a certain threshold, it is known that the electrodeshave been removed from the storage area 222 or pouch 16. The highreflectance area 224 beneath each PEPS 223 provides a signal that isboth a high intensity as well as being synchronous with the emitterdrive with low background level; thus it is possible to distinguish witha high degree of accuracy which, if either, of the electrodes 212, 214is still applied to the liner 216. When an electrode 212, 214 is removedfrom the liner 216 the background level of the signal increases due toambient light while the synchronous portion decreases because there islittle if any of the photoemitter light reflected back into thephotosensor; this condition describes when an electrode 212, 214 isremoved from the liner 216. When it has been determined that anelectrode 212, 214 has been removed from the liner 216, the processormeans 20 proceeds to the next state looking for application of thatelectrode to the patient. Application of the electrode 212, 214 to thepatient will result in a decrease in the background level of the signaloutput and some synchronous output level intermediate to the synchronouslevel measured when the electrode 212, 214 was still on the liner 216.If it has been determined that both electrodes 212, 214 are applied tothe patient but there is an impedance measured between the electrodesthat is significantly outside the normal physiological range then it isvery possible that the user has applied the electrodes to the patientwithout removing the patient's shirt. Surprisingly, this is not uncommonin real situations with users; a patient's shirt will have been onlypartially removed when electrodes are applied resulting in insufficientelectrical contact with the patient's skin. FIG. 6 d shows the flowchartfor prompting related to retrieval and application of electrodes. As inthe case with responding to a user's interactions.

In other implementations, the graphics on the center decal can beaccompanied by any desired light source. For instance, if desired, allof the graphics can be translucent, and can be backlit. Alternatively,the graphics can be provided in the form of LED images, rather than on adecal.

While the electrodes have been illustrated in the form of an integralelectrode assembly, separate electrodes may be used.

In some implementations, generally all of the graphically illustratedsteps are shown at the same time, e.g., as illustrated by the decaldescribed above. This arrangement allows the caregiver to see the stepsthat will be performed next and thus anticipate the next step and beginit early if possible. However, alternatively, the graphics can bedisplayed one at a time, e.g., by using a screen that displays onegraphic at a time or backlit graphics that are unreadable when not backlit. This arrangement may in some cases avoid overwhelming novice or layrescuers, because it does not present the caregiver with too muchinformation all at the same time.

If desired, each graphic could have an associated button that, whenpressed, causes more detailed audio prompts related to that graphic tobe output by the defibrillator.

The cover 12 of the AED may include a decal on its underside, e.g.,decal 200 shown in FIG. 11. Decal 200 illustrates the use of the coveras a passive airway support device, to keep the patient's airway openduring resuscitation. Graphic 202 prompts the caregiver to roll thepatient over and place cover 12 under the patient's shoulders, andgraphic 204 illustrates the proper positioning of the cover 12 under thepatient to ensure an open airway.

While such a graphic is not included in the decal shown in FIG. 5, thedecal 40 may include a graphic that would prompt the user to check tosee if the patient is breathing. Such a graphic may include, e.g., apicture of the caregiver with his ear next to the patient's mouth. Thegraphic may also include lines indicating flow of air from the patient'smouth.

“Illuminated”, “light up”, and similar terms are used herein to refer toboth a steady light and a light of varying intensity (e.g., blinking). Ablinking light may be used, if desired, to more clearly draw the user'sattention to the associated graphic.

Referring to FIG. 16, in other implementations, a home first aid devicemay be provided for providing instructions and therapy, as needed, for avariety of medical situations. In some implementations, the device wouldinclude: (a) a cover to the device whose removal the processor iscapable of detecting; (b) a series of bound pages 230 on the face of thedevice under the cover 12 with a detection means providing fordetermining to which page the bound pages have been turned; (c) aprocessor; (d) a speaker 232 providing audio output. The home first aiddevice may also include a portion of the device used specifically forstorage of items commonly used in the course of providing aid such asbandaids, bandages, splints, antiseptic, etc. The storage areapreferably takes the form of a partitioned tray 234. Alternatively, thestorage area may take the form of multiple pockets, pouches, straps, orslots. The storage area is partitioned into individual wells in whicheach of the items is stored. Photoelectric sensors 236, 237 may beprovided in each of the wells, thereby providing a means of determiningwhich, if any, of the items has been removed by the user. Detectingwhich page the bound pages are turned to may be provided by embeddingsmall high magnetic intensity samarium cobalt magnets 240 in locationsspecific to each page 242. In some implementations, the magnets 240 arelocated along the bound edge of the pages 242, outside the printed areaof the pages 242. Magnetic sensors 241 are located in the device housing14 that correspond to the locations where the magnets 240 located in thespecific pages 242 make contact when the specific page 242 is turned.The magnetic sensor 241 may be a semiconductor device employing the Halleffect principle, but may also be a reed switch or other magneticallyactivated switch. By providing a means of detecting user actionsautomatically such as the detection of which page the user has turned toor which first aid item has been removed from the storage container, thedevice is able to interact and respond to the rescuer in an invisiblemanner, improving both speed as well as compliance to instructions. Insuch a manner, interactivity is preserved while at the same timeproviding a printed graphical interface to the user.

In some implementations, a pressure sensor 321 (PS) may be provided(FIG. 3), e.g., the MPXV5004 pressure sensor manufactured by FreescaleSemiconductor. The MPXV5004 has trimmed outputs, built-in temperaturecompensation, and an amplified single-ended output, which make itcompatible with an Analog to Digital converter (A/D). The MPXV5004 usesa piezo-resistive pressure sensing element, which can produce shot(white) noise and 1/f (flicker noise). Shot noise is the result ofnon-uniform flow of carriers across a junction and is independent oftemperature. Flicker noise (1/f) results from crystal defects, and isalso due to wafer processing. This noise is proportional to the inverseof frequency and is more dominant at lower frequencies. Signalconditioning element 323 (FIG. 3) will filter out much of that noise.One possible circuit for accomplishing this filtering is shown in FIG.3A.

Using the pressure sensor 321 configured as a gauge-type sensor,ventilation rates can be detected from variations in the generatedpressure waveform. Conventional techniques may be used to process thepressure waveform to generate ventilation rate—e.g., template matching,bandpass filtering, or dynamic thresholding. The pressure sensor 321 mayalso be configured as a differential pressure sensor.

The pressure sensor may be located on the electrode pad assembly, asshown in FIG. 12. Tubing 215 is connected between the electrode assemblyand an adapter 219 positioned in the airway. If a differential pressuremeasurement is being made, two tubes 215 are brought from the adapter tothe electrode assembly. The adapter 219 has a small vane positionedbetween the pressure sensing ports so that the pressure differencegenerated between the two ports is proportional to the velocity of airflow through the adapter into the patient. Knowing the cross-sectionalarea of the air path through the adapter, allows the tidal volume to beestimated (using known differential pressure tidal volume measurementtechniques).

Having calculated the ventilation rate and tidal volume, it is possibleto detect whether or not the appropriate number and rate of breaths havebeen given as well as the proper amount of tidal volume. If theprocessor determines that the ventilation rate may be correct, but thetidal volume may be insufficient, a message may be generated, “Make sureto breathe more deeply into the patient” (prompt 13 in FIG. 7A). Similarmessages may also be provided to correct for incorrect ventilation rate.

In another implementation, an accelerometer 76 (FIG. 15) can be usedinstead of the pressure sensor. The accelerometer can be used to detectboth the CPR compressions and the ventilation rate. Sternal displacementdue to compressions has a high frequency leading edge and is initiallynegative (compression), while the ventilation cycle has a leading edgethat is approximately an order of magnitude lower in frequency (0.5 Hzvs. 5 Hz) than the compression cycle, and is positive (chest rising dueto lung inflation). Thus, ventilations can be distinguished fromcompressions, e.g., using a bandpass filter in the software detectionalgorithm. A limitation of this method is that accurate measurements oftidal volume would not normally be attainable.

In another implementation, the pressure sensor 21 can be combined with asecond sensor, such as accelerometer 76, to detect the common clinicalsituation in which the intubation tube, commonly called the endotracheal(ET) tube, has been improperly positioned into the stomach via theesophagus, rather than into the lungs via the trachea. It is also notuncommon for the ET tube to become dislodged during the course ofresuscitation, or as a result of vibrations during transport byambulance or other mode of transportation. Detection of a pressurewaveform pulse is used to initiate an analysis of either theaccelerometer waveform, the TTI waveform, or both to see if the attemptto deliver respiratory gas via ventilation is delivering the gas to thelungs or to the stomach (via the esophagus). If the gas is delivered tothe lungs, there will be an associated pulse waveform of the actualmeasured displacement of the sternal region where the accelerometer isplaced (double integration of the accelerometer waveform will show arising sternum). Alternatively, a TTI measurement can be used, as airdelivered to the lungs will cause a rise in transthoracic impedance(TTI). Due to both the compressible nature of the gas as well as thefact that the lungs expand both sternally and diaphragmatically, therewill be some delay following generation of the pressure pulse before theassociated displacement waveform is observed from the accelerometer orthe TTI measurement.

In some implementations, two pulse detection methods are used. The firsttime aligns the pressure waveform pulse with the pulse waveform of thesternal displacement and TTI measurement. If the delay from the leadingedge of the pressure pulse waveform to the leading edge of thedisplacement and TTI waveforms is less than 700 milliseconds, and thedelay of the trailing edge of the pressure pulse waveform to thetrailing edge of the displacement and TTI waveforms is also less than700 milliseconds, then the displacement and TTI pulse waveforms areconsidered to be as a result of the ventilation cycle. The second pulsedetection method uses the acceleration waveform to detect the firstinitial movement of the sternum due to the ventilation. The displacementwaveform is calculated, and the first pulse of the acceleration signalthat contributes to the displacement pulse determines the start of thesternal displacement pulse. A more accurate onset of motion of thesternum due to ventilation can oftentimes be achieved in this manner.

If the displacement and TTI waveforms are found to be the result of theventilation pressure waveform pulse, then the ET tube is considered tobe in the proper location in the trachea and not in the esophagus.

A visual indicator comparable to those shown in FIG. 12 may be locatedon the electrode assembly, providing visual feedback to the rescuer asto whether or not the ET tube has been properly placed. When the tube isdetermined to be properly placed, the processing means may activate agreen LED on the electrode assembly. If the previous ventilation attemptresulted in the determination of an improperly placed ET tube, then theprocessing means may activate a red LED of the visual indicator. Thevisual indicator may also include a series of LEDs configured as a dualcolor bar-graph to indicate the tidal volume of each successiveventilation, with the color of the LED bars indicative of whether or notthe tube is properly placed (green indicating proper placement;red-indicating improper placement). Alternatively, separate indicatinglights may be provided for airway and breathing, to indicate proper ETtube placement and ventilation tidal volume, respectively.

Many other implementations are within the scope of the following claims.

1. An automatic external defibrillation device for delivering defibrillation shocks to a patient and for assisting a caregiver in delivering cardiac resuscitation to the patient, the device comprising an electrode pad supporting at least one defibrillation electrode, the pad being configured to be adhesively applied to the chest of the patient; at least one airway pressure sensor configured to detect information relating to the caregiver's delivery of ventilations to the patient; wherein at least a portion of the airway pressure sensor is mounted on the electrode pad; a processor configured to process the output of the airway pressure sensor to determine a parameter descriptive of ventilation progress.
 2. The device of claim 1 wherein the parameter descriptive of ventilation progress is ventilation rate, and the ventilation progress prompt comprises an instruction pertaining to varying the ventilation rate.
 3. The device of claim 1 wherein the parameter descriptive of ventilation progress is delivered tidal volume, and the ventilation progress prompt comprises an instruction pertaining to varying the delivered tidal volume.
 4. The device of claim 1 wherein the parameter descriptive of ventilation progress is flow rate, and the ventilation progress prompt comprises an instruction pertaining to varying the flow rate.
 5. The device of claim 1 wherein at least one tube runs from the airway pressure sensor on the electrode pad to an adapter configured to be positioned in the vicinity of the patient's mouth, and the tube and adapter are configured so that a pressure associated with ventilations is conveyed through the tube to the airway pressure sensor on the electrode pad assembly.
 6. The device of claim 5 further comprising a second tube running from the airway pressure sensor to the adapter, and the adapter and tubes are configured to measure a differential pressure associated with ventilations.
 7. The device of claim 1 further comprising at least one indicator light on the electrode pad assembly to convey information about delivered ventilations.
 8. The device of claim 7 wherein the information comprises whether ventilation rate is within a predetermined range of acceptable ventilation rates.
 9. The device of claim 7 wherein the information comprises an indication of the delivered tidal volume.
 10. A device for assisting a caregiver in delivering cardiac resuscitation to a patient, the device comprising a user interface configured to deliver prompts to a caregiver to assist the caregiver in delivering cardiac resuscitation to a patient; at least two sensors configured to provide signals from which information can be derived on the placement of an ET tube in the patient; a memory in which a plurality of different prompts are stored, including at least a first ET tube placement prompt providing a first indication as to the placement of the ET tube; a processor configured to process the outputs of the sensors to determine the ET tube placement and to determine whether the first ET tube placement prompt should be delivered.
 11. The device of claim 10 wherein the first ET tube placement prompt comprises a prompt indicating that the ET tube is not correctly placed in the patient's trachea.
 12. The device of claim 10 wherein the sensors comprise a pressure sensor configured to detect the timing of ventilations delivered to the ET tube and an accelerometer configured to detect sternal motion in the patient.
 13. The device of claim 10 wherein the sensors comprise a pressure sensor configured to detect the timing of ventilations delivered to the ET tube and a TTI sensor configured to detect changes in the transthoracic impedance of the patient.
 14. The device of claim 10 wherein one of the sensors is configured to detect the timing of ventilations delivered to the ET tube, another of the sensors is configured to detect the timing of sternal movement in the patient or of change in transthoracic impedance of the patient, and the processor is configured to compare the relative timing of ventilations and sternal movements or transthoracic impedance changes. 